The present invention relates to a machine tool having a specific cover device.
Japanese patent publication No. 365529 of 1992 discloses a machine tool capable of shortening the length of a spindle direction (namely, longitudinal direction) of the first saddle, the second saddle, and a column, and of moving a spindle head in longitudinal direction at high speed. As shown therein, the machine tool is defined that the column is fixedly installed on a bed in the spindle direction and guides the first saddle to move in vertical direction. Besides, the first saddle guides the second saddle to move in lateral direction, and the second saddle guides the spindle head to move in longitudinal direction.
In the above machine tool, when a tool installed on the front end of the spindle head cuts a workpiece, cutting chips and coolant sometimes splash backward due to rotations of the tool. Without any protection from this splash, cutting chips of the workpiece and tile coolant fall directly on the first saddle and the second saddle. As a result, not only machining accuracy is damaged, but also maintenance and cleaning of the machine tool are made difficult.
An object of the invention is to provide a machine tool having a specific cover device free from the above problems.
To achieve the above object, a machine tool of this invention has the following characters. A column is fixedly installed on a bed, and the first saddle is guided on the front surface of the column movably in vertical direction. The second saddle is guided on the front surface of the first saddle movably in lateral direction, and tile spindle head is guided on the second saddle movably in longitudinal direction. To the front surface of the second saddle is fixed the first cover plate which allows the spindle head to move in longitudinal direction. A side cover plate is connected to each of the right and left side edges of the cover plate in such a manner that the side cover plate can bend backward due to guiding effect of a guiding means provided between the side cover plate and the first saddle. The second cover plate covers the front side, tie upper side and the lower side of tile first cover plate in such a manner that the spindle head can move in lateral direction. The second cover plate is fixed integrally with the first saddle, and the third cover plate is fixedly installed to the front side of the second cover body. The third cover plate covers the front surface of the column in such a manner that the spindle head can move in vertical and lateral directions.
The above first cover plate, side cover plate, second cover plate and third cover plate can prevent cutting chips and coolant which splash from the tip of the spindle head from falling directly on the rear part of the spindle head, the first saddle and the second saddle.
Besides, when the second saddle moves in lateral direction, the right and left side cover plates are prevented from bending backward and from protruding in lateral direction.
More concretely, the first cover plate has a through hole into which the spindle head is inserted movably in longitudinal direction. A sealing means is provided between the through hole and tile spindle head, thereby keeping an interval therebetween almost liquid-tightly. With this structure, cutting chips and coolant splashing backward from the tip end of the spindle head are prevented from getting in the back of the spindle head through the interval between the through hole and the spindle head.
Circular guide passages are provided to the guiding means provided between tile side cover plate and the first saddle.
Moreover, when the second saddle moves to either of the right and left sides, the side cover plate on the side to which the first saddle moves bends backward centering on a position connecting with the first cover plate due to guiding effects of circular guide passages of the guiding means.
Besides, the side cover plate is pulled in a direction perpendicular to the circular guide passages of the guiding means by forcing means. This structure controls shake due to free space of an operating part of the side cover plate.
On the other side, the side cover plate may be formed from plural cover plate members, and these cover plate members are bendably connected with each end.